blending multiple exposures

[Ofnuts]

I think @Pixlab means this.

However this doesn't really explain how I did it.

To the OP: multiple exposure is not done by averaging the pictures. It is done by completely masking some base frame with extracts from the other frames.

So, you stack all you pictures in Gimp, and in all the frames except the bottom one you extract the dog, using a layer mask.

It is much easier when there is no overlap between the various instances of the dog, because in that case you don't need a very accurate cut (uncut pixels being the background, identical in all frames). Unfortunately you do have some overlap to you will have to do a fairly accurate cut. Given the fluffy nature of the tail, I would to the stacking with first image at the top:

• This puts the head if image N over the tail of image N-1
  
• That makes the head the more visible part, which is cool since it is also the most important
  
• You only need an accurate cut around the head and front legs, where they overlap the tail of the next frame, and cutting around the head which isn't fluffy is going to be somewhat easy, while the fluffy tail can be dealt with with a very rough cut around it.
  

For instance this is how I would cut the 2nd frame (which is also the 2nd from top): accurate cut on head/chest and front legs, but very rough cut at the rear where the accuracy of the overlap depends on the cut of the first frame. And this is one of the worst case of overlap that you have, the others should be simpler.